From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A843BC2D0DC for ; Thu, 2 Jan 2020 16:46:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 70E1C206E6 for ; Thu, 2 Jan 2020 16:46:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577983563; bh=qlFond1EFVLGLYfXXx4xXrL9qrocvPjeOrRiyzot7IA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=iMfVUbDfjxnCp2BxG4njM6oeHgrgEBnSflHL3Cvqpf/2vIokgjSIm7cr95/GyO7fd 6i+bCz4LZIfr/110xpyzkWWL+r5b/TacMQC+ARaxYaKsIxk6jJfmJHDT6G/5z7Sc8D JA4J35px65bX0RbCY7i1sapZK03d3jZ2+zh7VQkU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728824AbgABQqC (ORCPT ); Thu, 2 Jan 2020 11:46:02 -0500 Received: from mail-qk1-f195.google.com ([209.85.222.195]:43370 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728280AbgABQqC (ORCPT ); Thu, 2 Jan 2020 11:46:02 -0500 Received: by mail-qk1-f195.google.com with SMTP id t129so31763054qke.10 for ; Thu, 02 Jan 2020 08:46:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=iiqyRUxApX19Ui9kuOhGNxpjioocaGgUbk2e+WSV8hE=; b=PPfQ8dkLcgB5s1uIw5s482KYoJ0kfle4CwFAbokQN/faGx281rxxNTK/RwRo/tSqF/ tN2RciXIfqDICxSKGrt0CAPK46OUW9xqnCjn3k+ECKgdkCqYUK/zoBofAd5TnQDYPpu9 fcqQJ0exzxFEQn9kfi+oIACMbKwmH1UIoH4X/ZRcP1on9kXCmqSbILoljkQWb5XrNuCA zhFt8QEFQmaoAiZp5mFUcjbxJbwVYs/Hd8VexYftvkQ/05iv4/I6/89wxj9IeNaBiz+/ stSy1dwLXyCT1qRMOaybvUX1bwgPtWuxsCuRPSEUrX+szCzksEyoxg/4OJOoAofHe3hL pUGQ== X-Gm-Message-State: APjAAAXSJl7ILO8lfVAA8AW50bjlzm1pIpxOSnSsMOAa7QCN1N6BckZW 7gEeKA72MPBiZz8rR5IapCk= X-Google-Smtp-Source: APXvYqz4FxyKw4nQF5lp/s8Zw4Z5hkl/1Q84Pv2c/GcNCa27nXYbYHv1lrUG4+tnxOkmbjYTlcVTpQ== X-Received: by 2002:a05:620a:1522:: with SMTP id n2mr66663430qkk.108.1577983560885; Thu, 02 Jan 2020 08:46:00 -0800 (PST) Received: from dennisz-mbp.dhcp.thefacebook.com ([2620:10d:c091:500::1:29bb]) by smtp.gmail.com with ESMTPSA id s91sm16953837qtd.50.2020.01.02.08.45.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Jan 2020 08:46:00 -0800 (PST) Date: Thu, 2 Jan 2020 11:45:58 -0500 From: Dennis Zhou To: David Sterba Cc: Dennis Zhou , David Sterba , Chris Mason , Josef Bacik , Omar Sandoval , kernel-team@fb.com, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 13/22] btrfs: calculate discard delay based on number of extents Message-ID: <20200102164558.GA86832@dennisz-mbp.dhcp.thefacebook.com> References: <20191230165043.GV3929@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191230165043.GV3929@twin.jikos.cz> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Dec 30, 2019 at 05:50:43PM +0100, David Sterba wrote: > On Fri, Dec 13, 2019 at 04:22:22PM -0800, Dennis Zhou wrote: > > Use the number of discardable extents to help guide our discard delay > > interval. This value is reevaluated every transaction commit. > > This is too short compared to the added code, please enhance it eg. by > briefly describing what values are tracked and how are they related > together. > Done. > > Signed-off-by: Dennis Zhou > > Reviewed-by: Josef Bacik > > --- > > fs/btrfs/ctree.h | 2 ++ > > fs/btrfs/discard.c | 53 ++++++++++++++++++++++++++++++++++++++---- > > fs/btrfs/discard.h | 1 + > > fs/btrfs/extent-tree.c | 4 +++- > > fs/btrfs/sysfs.c | 31 ++++++++++++++++++++++++ > > 5 files changed, 86 insertions(+), 5 deletions(-) > > > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > > index 18df0e40a282..98979566e281 100644 > > --- a/fs/btrfs/ctree.h > > +++ b/fs/btrfs/ctree.h > > @@ -469,6 +469,8 @@ struct btrfs_discard_ctl { > > struct list_head discard_list[BTRFS_NR_DISCARD_LISTS]; > > atomic_t discardable_extents; > > atomic64_t discardable_bytes; > > There are some type mismatches for the two: > > > + u32 delay; > > + u32 iops_limit; > > unsigned for iops I switched iops_limit to unsigned and delay to unsigned long. > > > }; > > > > /* delayed seq elem */ > > diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c > > index e8c2623617fd..160713e04d0c 100644 > > --- a/fs/btrfs/discard.c > > +++ b/fs/btrfs/discard.c > > @@ -15,6 +15,11 @@ > > #define BTRFS_DISCARD_DELAY (120ULL * NSEC_PER_SEC) > > #define BTRFS_DISCARD_UNUSED_DELAY (10ULL * NSEC_PER_SEC) > > > > +/* Target completion latency of discarding all discardable extents. */ > > +#define BTRFS_DISCARD_TARGET_MSEC (6 * 60 * 60UL * MSEC_PER_SEC) > > +#define BTRFS_DISCARD_MAX_DELAY (10000UL) > > +#define BTRFS_DISCARD_MAX_IOPS (10UL) > > All unsigned longs > I've switched BTRFS_DISCARD_MAX_IOPS to 10U and lowered the max delay to be 1s from our previous conversation. > > + > > static struct list_head *get_discard_list(struct btrfs_discard_ctl *discard_ctl, > > struct btrfs_block_group *block_group) > > { > > @@ -239,11 +244,18 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, > > > > block_group = find_next_block_group(discard_ctl, now); > > if (block_group) { > > - u64 delay = 0; > > + u32 delay = discard_ctl->delay; > > + > > + /* > > + * This timeout is to hopefully prevent immediate discarding > > + * in a recently allocated block group. > > + */ > > + if (now < block_group->discard_eligible_time) { > > + u64 bg_timeout = (block_group->discard_eligible_time - > > + now); > > > > - if (now < block_group->discard_eligible_time) > > - delay = nsecs_to_jiffies( > > - block_group->discard_eligible_time - now); > > + delay = max_t(u64, delay, nsecs_to_jiffies(bg_timeout)); > > delay is u32, nsecs_to_jiffies returns unsigned long, so delay should be > also unsigned long everywhere. > > > + } > > > > mod_delayed_work(discard_ctl->discard_workers, > > &discard_ctl->work, > > @@ -348,6 +360,37 @@ bool btrfs_run_discard_work(struct btrfs_discard_ctl *discard_ctl) > > test_bit(BTRFS_FS_DISCARD_RUNNING, &fs_info->flags)); > > } > > > > +/** > > + * btrfs_discard_calc_delay - recalculate the base delay > > + * @discard_ctl: discard control > > + * > > + * Recalculate the base delay which is based off the total number of > > + * discardable_extents. Clamp this with the iops_limit and > > + * BTRFS_DISCARD_MAX_DELAY. > > + */ > > +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) > > +{ > > + s32 discardable_extents = > > + atomic_read(&discard_ctl->discardable_extents); > > + s32 iops_limit; > > signed for iops > > > + unsigned long delay; > > + > > + if (!discardable_extents) > > + return; > > + > > + spin_lock(&discard_ctl->lock); > > + > > + iops_limit = READ_ONCE(discard_ctl->iops_limit); > > unsigned -> signed > > > + if (iops_limit) > > + iops_limit = MSEC_PER_SEC / iops_limit; > > + > > + delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; > > + delay = clamp_t(s32, delay, iops_limit, BTRFS_DISCARD_MAX_DELAY); > > + discard_ctl->delay = msecs_to_jiffies(delay); > > unsigned long -> u32 > > > + > > + spin_unlock(&discard_ctl->lock); > > +} > > + > > /** > > * btrfs_discard_update_discardable - propagate discard counters > > * @block_group: block_group of interest > > @@ -476,6 +519,8 @@ void btrfs_discard_init(struct btrfs_fs_info *fs_info) > > > > atomic_set(&discard_ctl->discardable_extents, 0); > > atomic64_set(&discard_ctl->discardable_bytes, 0); > > + discard_ctl->delay = BTRFS_DISCARD_MAX_DELAY; > > + discard_ctl->iops_limit = BTRFS_DISCARD_MAX_IOPS; > > } > > > > void btrfs_discard_cleanup(struct btrfs_fs_info *fs_info) > > diff --git a/fs/btrfs/discard.h b/fs/btrfs/discard.h > > index 7e3680dd82ce..3ed6855e24da 100644 > > --- a/fs/btrfs/discard.h > > +++ b/fs/btrfs/discard.h > > @@ -17,6 +17,7 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, > > bool btrfs_run_discard_work(struct btrfs_discard_ctl *discard_ctl); > > > > /* Update operations. */ > > +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl); > > void btrfs_discard_update_discardable(struct btrfs_block_group *block_group, > > struct btrfs_free_space_ctl *ctl); > > > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > > index 2c12366cfde5..0163fdd59f8f 100644 > > --- a/fs/btrfs/extent-tree.c > > +++ b/fs/btrfs/extent-tree.c > > @@ -2935,8 +2935,10 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans) > > cond_resched(); > > } > > > > - if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) > > + if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) { > > + btrfs_discard_calc_delay(&fs_info->discard_ctl); > > btrfs_discard_schedule_work(&fs_info->discard_ctl, true); > > + } > > > > /* > > * Transaction is finished. We don't need the lock anymore. We > > diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c > > index e799d4488d72..79139b4b4f0a 100644 > > --- a/fs/btrfs/sysfs.c > > +++ b/fs/btrfs/sysfs.c > > @@ -344,6 +344,36 @@ static const struct attribute_group btrfs_static_feature_attr_group = { > > */ > > #define discard_to_fs_info(_kobj) to_fs_info((_kobj)->parent->parent) > > > > +static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj, > > + struct kobj_attribute *a, > > + char *buf) > > +{ > > + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); > > + > > + return snprintf(buf, PAGE_SIZE, "%u\n", > > + READ_ONCE(fs_info->discard_ctl.iops_limit)); > > +} > > + > > +static ssize_t btrfs_discard_iops_limit_store(struct kobject *kobj, > > + struct kobj_attribute *a, > > + const char *buf, size_t len) > > +{ > > + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); > > + struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl; > > + u32 iops_limit; > > + int ret; > > + > > + ret = kstrtou32(buf, 10, &iops_limit); > > + if (ret) > > + return -EINVAL; > > + > > + WRITE_ONCE(discard_ctl->iops_limit, iops_limit); > > + > > + return len; > > +} > > +BTRFS_ATTR_RW(discard, iops_limit, btrfs_discard_iops_limit_show, > > + btrfs_discard_iops_limit_store); > > + > > static ssize_t btrfs_discardable_extents_show(struct kobject *kobj, > > struct kobj_attribute *a, > > char *buf) > > @@ -367,6 +397,7 @@ static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj, > > BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show); > > > > static const struct attribute *discard_debug_attrs[] = { > > + BTRFS_ATTR_PTR(discard, iops_limit), > > BTRFS_ATTR_PTR(discard, discardable_extents), > > BTRFS_ATTR_PTR(discard, discardable_bytes), > > NULL, > > -- > > 2.17.1